Radar device and corresponding operating method

Abstract

In accordance with a first aspect of the present disclosure, a radar device is provided, comprising: a plurality of receiver channels; a plurality of mixers, wherein each of the receiver channels comprises one of said mixers; a first frequency synthesizer configured to generate a chirp signal; at least one test tone generator configured to generate a test tone signal having a constant frequency; wherein said mixers are configured to be fed with said chirp signal and with the test tone signal. In accordance with a second aspect of the present disclosure, a corresponding method of operating a radar device is conceived.

1 - 14 . (canceled) 
     
     
         15 . A radar device, comprising:
 a plurality of receiver channels;   a plurality of mixers, wherein each of the receiver channels comprises one of said plurality of mixers;   a first frequency synthesizer configured to generate a chirp signal; and   at least one test tone generator configured to generate a test tone signal having a constant frequency, wherein said plurality of mixers are configured to be fed with said chirp signal and with the test tone signal.   
     
     
         16 . The radar device of  claim 15 , further comprising at least one transmitter, wherein the test tone generator is coupled to the transmitter through a switch. 
     
     
         17 . The radar device of  claim 15 , wherein the test tone generator is coupled to the receiver channels through a built-in self-test, BIST, structure. 
     
     
         18 . The radar device of  claim 15 , wherein the test tone generator is implemented as a second frequency synthesizer, wherein said second frequency synthesizer is embedded in a follower integrated circuit, IC, of the radar device. 
     
     
         19 . The radar device of  claim 15 , wherein said receiver channels are distributed over multiple ICs, and wherein each of the ICs comprises a test tone generator coupled to the respective receiver channels of said ICs through a BIST structure of said ICs. 
     
     
         20 . The radar device of  claim 15 , further comprising a post-processing unit configured to derive time offsets between the receiver channels from digitized output signals provided by the mixers. 
     
     
         21 . The radar device of  claim 20 , wherein the post-processing unit is configured to compute a set of fast Fourier transforms, FFTs, of said digitized output signals. 
     
     
         22 . The radar device of  claim 21 , wherein the post-processing unit is configured to multiply, for given pairs of the receiver channels, the FFTs in the frequency domain and to compute a corresponding phase of sub-carriers. 
     
     
         23 . The radar device of  claim 22 , wherein the post-processing unit is configured to fit phase-over-frequency data derived from the computed phase of the sub-carriers by a first-order polynomial whose slope is a measure of the time offsets. 
     
     
         24 . The radar device of  claim 20 , wherein the receiver channels comprise analog-to-digital converters configured to digitize the output signals provided by the mixers. 
     
     
         25 . The radar device of  claim 20 , wherein the receiver channels comprise filters configured to filter the output signals provided by the mixers. 
     
     
         26 . A vehicle comprising the radar device of  claim 15 . 
     
     
         27 . A method of operating a radar device, comprising:
 generating, by a first frequency synthesizer included in the radar device, a chirp signal;   generating, by at least one test tone generator included in the radar device, a test tone signal having a constant frequency; and   feeding mixers included in receiver channels of the radar device with the chirp signal and the test tone signal.   
     
     
         28 . The method of  claim 27 , further comprising deriving, by a post-processing unit included in the radar device, time offsets between the receiver channels from digitized output signals provided by the mixers. 
     
     
         29 . The method of  claim 28 , further comprising computing, by the post-processing unit, a set of fast Fourier transforms, FFTs, of said digitized output signals. 
     
     
         30 . The method of  claim 29 , further comprising:
 performing, by the post-processing unit, frequency domain multiplication of the FFTs for given pairs of the receiver channels; and   computing, by the post-processing unit, a corresponding phase of sub-carriers.   
     
     
         31 . The method of  claim 30 , further comprising fitting, by the post-processing unit, phase-over-frequency data derived from the computed phase of the sub-carriers by a first-order polynomial whose slope is a measure of the time offsets. 
     
     
         32 . The method of  claim 28 , further comprising digitizing, by analog-to-digital converters of the receiver channels, the output signals provided by the mixers. 
     
     
         33 . The method of  claim 28 , further comprising filtering, by filters of the receiver channels, the output signals provided by the mixers.